Scientists have developed a new superelastic alloy or SEA, that has the capacity to regain its original shape even after exposure under extreme temperature conditions. The iron-based SEA can withstand temperatures past traditional points of critical stress and it a cost-effective alternative to conventional SEAs.
These findings, published in Science from researchers from Tohoku University's Graduate School of Engineering, overcome the limits of expensive metal-based SEAs such as Ti-Ni, which require temperatures lower than -20C or higher than 80C.
“The discovery possesses wide-spread application for outer-space exploration given the large temperature fluctuations that occur," says Associate Professor at Tohoku University, Toshihiro Omori.
Professor Omori and his team describe the SEA system they have developed, citing it as Fe-Mn-Al-Cr-Ni. They write in their study that what makes Fe-Mn-Al-Cr-Ni unique is its temperature balance. “Temperature dependence is a common feature that often restricts the use of metal shape memory alloys in applications. We discovered an iron-based superelastic alloy system in which the critical stress can be optimized,” say the authors.
While most SEAs have a positive temperature dependence, meaning the critical stress increases as the temperature rises, the team figured out that adding more Chromium to Fe-Mn-Al-Cr-Ni shifted the temperature dependence from a positive to a negative. As explained by Eureka Alert, “Balancing the Chromium content resulted in zero temperature dependence with the critical stress remaining almost constant at various temperatures.”
They say that its durability under extreme temperatures could play a part in developing a superelastic tire for missions to Mars and to the Moon, where temperatures range from -150C to 20C and -170C to 120C respectively.
"Yet, the new, SEA's usage does not stop there." Professor Omori comments, "It can potentially be used in tension braces in buildings or column elements in bridges - providing greater resistance to earthquakes."